1. Field of the Invention
The present invention relates to a wireless communication, and more particularly, to a sounding reference signal transmission performed by a wireless device to which a plurality of serving cells are configured.
2. Related Art
In a wireless communication system, a duplex scheme includes a time division duplex (TDD) and a frequency division duplex (FDD). The TDD provides an uplink communication and a downlink communication in the same frequency band. The FDD provides the uplink communication and the downlink communication in different frequency bands.
A carrier aggregation is a technique capable of providing a plurality of component carriers to a user equipment. Each component carrier may be defined as one cell. When the plurality of component carriers are configured to the user equipment, it can be regarded that the user equipment receives services from a plurality of serving cells.
Each serving cell may be configured with the FDD or the TDD. In a carrier aggregation environment, the user equipment may be configured with a plurality of duplex schemes. For example, if two cells are configured to the user equipment, the cells may be configured as a TDD cell-TDD cell or a TDD cell-FDD cell. Accordingly, a throughput of the user equipment can be increased in various network environments.
The conventional uplink signal transmission does not consider an environment in which a plurality of serving cells using different duplex schemes are configured.